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An anonymous reader writes "British scientists have announced their intent to build a Star Trek-style magnetic shielding system to help protect astronauts from radiation. 'There are a variety of risks facing future space explorers, not least of which is the cancer-causing radiation encountered when missions venture beyond the protective magnetic envelope, or magnetosphere, which shields the Earth against these energetic particles. The Earth's magnetosphere deflects many of these particles; others are largely absorbed by the atmosphere.'"

This was reported on slashdot three years ago [slashdot.org]. The space.com article linked to from the 2004 slashdot summary is actually much more detailed in terms of the science. The big engineering problems with this approach still have not been solved. (1) If you're not using superconducting magnet coils, a large, static magnetic field requires a huge power supply to keep it going. That's not practical for foreseeable, near-future technologies for going to Mars, which will need to use very small payloads. (2) Superconducting magnets are unreliable, finicky beasts, at least from my experience here on earth. You need big, heavy cryostats full of liquified gases. It's not necessarily a good idea to have a vital piece of safety equipment for your spaceship depend on an inherently high-maintenance, low-reliability technology. (3) Large electric fields are hard to maintain because you get arcing and discharges. I used to work at an electrostatic accelerator that used megavolt potentials, and it would start sparking at the most inopportune times, for reasons like, e.g., someone leaving behind a speck of lint inside the accelerator. When a spark would happen, you could hear it all through the building, and the energy released was equivalent to dropping a VW bug off the roof of a building. Again, low-reliability, high maintenance. (4) Although it's possible to use tricks to get rid of some of the particles, or channel particles to a place where they're not as harmful, you still have to deal with the fact that you have particles with both signs of charge, which feel forces in opposite directions from the same field. What repels one attracts the other. Also, if the particles get channeled to a certain place, and impact on something solid, then you get extremely intense secondary radiation at that spot.

So does that mean when went sent people to space before, they got exposed to all kinds of particals and stuff? Are they still ok? If so, then do we really need this?
Or....did we fake the moon stuff?Galactic cosmic rays [wikipedia.org] are the biggest, most difficult problem. For a variety of reasons, explained in the WP link, they're not a big problem for low-earth orbit space stations like the ISS. The Apollo astronauts did get exposed to a lot of radiation, but they were only out for about a week, whereas an elliptical transfer orbit to Mars takes 1.4 years round trip in interplanetary space. For anyone who's actually had to wear a radiation badge to work, the integrated dosages they've estimated for a Mars issue just sound nuts, like somebody moved a decimal place over three places by mistake. It's a huge amount of radiation, roughly on the right order of magnitude to kill a human being. The Apollo astronauts got dosages at the level where there's speculation they may be getting cataracts at a significantly higher rate than normal. Scale that up by a ratio of 1.4 years to 1 week, and you get effects that are just not on the order of magnitude that you could laugh off heroically.

Scale that up by a ratio of 1.4 years to 1 week, and you get effects that are just not on the order of magnitude that you could laugh off heroically.

And that's just one of many knowns and quite a few unknowns. Your whole body will be quite fucked up by all the zero/low-G. Anything goes wrong, you might end up as everything from a tin can in space to a smear on Mars' surface to the first permanent resident on Mars. Even on the most deserted arctic outpost you don't get crammed up in so little space for a so long time. But with all that and more - if NASA called me up and said "If you pass all the tests, you'll be the first man on Mars" I'd go striaght into a three year exercise program. Really. Not for the second mission to mars though. Everybody knows Neil Armstrong. Some remember "Buzz" Aldrin. But the rest aren't remembered by anyone without at least a passing interest in space travel.

Yeah, active shielding (what they're talking about here) is all nice and good (if you can actually get it to work light enough and with low enough power) against solar radiation, but it's pretty useless against GCR (galactic cosmic radiation). There's a lot less GCR than solar radiation, but still enough that you're going to want to be shielded from it on a Mars mission. Which means that you still need passive shielding. Using passive shielding raises a whole host of design problems when weight is a consideration. One of the biggest is Bremsstrahlung; your best shielding tends to come from metals, so aluminum is a good choice, but GCR can kick off a storm of lower energy particles as it passes through, potentially becoming even more dangerous. In general, therefore, you want a multilayered design (plastics, water, or hydrogen fuel being the other major component -- anything hydrogen-rich), but that gets complex when you're not just looking at a one-dimensional situation, and when the necessary mechanical parts get involved.

How to deal with the radiation is one of the biggest issues that needs to be dealt with before a manned mission to Mars takes off. It truly is an unsolved problem that still needs a lot of work. Hopefully there is a good solution.

Indeed, if by "a few types of radiation" you mean, "no types of radiation at all."

Not correct: it will not work for neutral radiation (neutron and gamma) but will deflect charged particle radiation just fine.

And doesn't technically deflect anything away, but instead traps stuff. causing the particles to precipitate at specific locations (which can be more heavily shielded) at the poles.

It is a real shame that nobody thought to tell us physicists about this because we have been using magnetic fields to deflect charged particles for years. Whether or not a particle is trapped (or where it is deflected to) depend entirely on the shape of the magnetic field and the momentum and charge of the incoming particle. You can trap particles but it is by no means a requirement.

Interestingly with a high enough magnetic field you can actually affect neutral atomic matter through: see this video [youtube.com] of a floating frog. This is due to an effect called diamagnetism [wikipedia.org] (not paramagnetism which the video claims it is). It is certainly the case that the fields they are considering are no where near enough for this to be a noticeable effect but if they could increase the strenght a few orders of magnitude (and shield the astronauts) you might start being able to have something a little more Star Trek like.